1. Field of the Invention
The present invention is directed to a screen assembly for vibrating screen machinery. In particular, the present invention is directed to a vibrating screen assembly for vibrating machinery wherein a plurality of screen layers are positioned on an improved frame and secured to the frame for improved efficiency, rigidity and durability.
2. Prior Art
Vibrating shakers utilize a screen assembly or assemblies to separate solid material from liquids and fine solid particles. The screen assembly is typically secured in and to the vibrating machinery through use of a frame. The frame is removably attached to the vibrating shaker. A mixture of materials is delivered or fed to the top of the screen assembly. The screen assembly is vibrated by a motor to vibrate the screen assembly at a high frequency.
The force of gravity separates the liquid and particles smaller than the pore size of the smallest screen layer. The screen assembly may be inclined so that the solids larger than the "cut point" will move across the screen where they are gathered and disposed of. At the same time, the liquid and particles smaller than the cut point will pass through the screen assembly and will also be collected.
The vibrating shaker machines are often used at remote locations, such as oil well drilling sites. The replacement screen assemblies must, thus, be transported great distances to these remote locations. A relatively lightweight screen assembly is, therefore, desirable.
Since the screen assembly must be transported and then installed in the field, any sharp edges on the screen assembly should be minimized.
There are various types of screen assemblies having various frames. In one configuration, a plurality of screen cloth layers are attached to a perforated plate which is, in turn, connected to the frame. The perforated plate has a large number of small openings to minimize the unsupported spans of screen cloth. It is important to achieve good adhesion between the perforated plate and the frame. Thus, the frame must have an adequate amount of planar surface to mate securely with the perforated plate.
The screen assembly is subject to tremendous stresses by virtue of the machinery vibrating it. Additionally, the screen assembly is subject to stresses from the weight of the material to be separated on the top layer of the screen. It is known that the screen assemblies will wear from usage and have a certain useful life, often in hours.
In order to balance screen life with through-put, it has been known to secure multiple layers of wire screen cloth to a perforated panel. The perforated panel is, in turn, secured to the frame. In the manufacturing process, the perforated panel and accompanying screens must be accurately aligned before adhesively bonding to the frame. It would be desirable to provide a self-alignment mechanism to align the perforated plate with the frame.
It is a principal object and purpose of the present invention to provide a vibrating screen assembly having a frame which will position the perforated panel thereon during the assembly process and discourage separation of the frame from the perforated panel.
It is an additional object and purpose of the present invention to provide a vibrating screen assembly with a blunt, safe edge around the perimeter to prevent personnel injury.
It is an additional object and purpose of the present invention to provide a vibrating screen assembly with good adhesion between the frame and the perforated plate.
It is a further object and purpose of the present invention to provide a vibrating screen assembly that will have a maximum useful life while being simple and inexpensive to manufacture.
It is a further object and purpose of the present invention to provide a screen assembly having a strong frame which will provide strength from side to side and provide strength from end to end.